Telephone system



June 30, 1931. J. ST-ICH TELEPHONE SYSTEM Filed May 15. 1930 w% E? N5 v m R uwmmx W NN 0 Patented June 30, 1931 PATENT] o FFICE;

JonAivNEssTron, or BEnLInGERMANY, AssIeNoR o sIEMENsez nALsKE AKT IEls- 'GESELLSOI-IAFT, or sIEM nssTAnT'B'n BERLINQGERMANY TELELLPHONE SYSTEM I Applicationfiled May 13,1930, Serial No. 452,087, and. in G-ermany. .Tune"6; 1 929.

For telephone systems with several ex- 7 changes and automaticworking it is known that the connections extending over several exchanges are completed. by anfoperatorin the exchange to which the wantedstation is connected. 'When new in the exchange of the wanted subscriber there are separate connecting devices provided .for local calls be 7 tween subscribers of the exchange; and for 10 calls coming from other exchanges, difliculties occur when the switches, over which the incoming calls extend, instead ofzbeing positioned by number impulses, are positioned *by designating the contact of the wanted line, for which the switch hunts.

Difficulties occur more especially if, when an'incoming call is set up andthe wanted subscrib'e fis lineis engaged, the existing connection must not be affected at first, this for example being the casefwhen, as inprivate branch exchanges,'the value ofthe existing connection cannot be ascertained forthwith,

because the switches cannot or must notbe provided with correspondingly arranged testing devices;

N ow the invention enables incomingcalls to be made fully effective in'particularly suitable, simple and reliably operating man- =ner,;b'ecause after the wantedline has been designated-by the operator,- the switching -operationsforreaching the Wanted subscribers line, that is to say for example the posi- 'tioning of the wipersfof the switch onto the efi'ected' over separate switching members of the switch." v i economicadvantages. For example it is unnecessary to provide the subscribers lines with special signals whereby before completingv incoming connectionstheoperator can recognize the engaged. condition of the wanted. subscribers line. v p u I I Furthermore, when 'exlsting'systems having only one exchangeare extendedby'the p I 1 The. lightingofthe lamp notifies the opera tor that a main exchange callf has arrived.

erection of additional'exch anges it is, pos

' sible to let the junction trafiicfbetweenthe I stationary bank contacts, and the ascertain ing of the engaged condition of this line are exchanges be supervised by an operatorfwithout anyalteration ofthe existing plant.

By suitably carrying out the invention it is also'possible, when the wanted subscrib ers station. i engaged,rfor the; operator, who

sets up the incoming call, to communicate .:over the positionedswitch with the speaking subscribers for the purpose of releasing the existing connection, thus inthese; cases iti's 60 not necessary to set up aseparate connection between the voperatorand the engaged subexchanges wlth stepping I changeYHV is only showna call seeker ASl by its three wipers m2, 62,02, the test relay Pas and the feeding bridge relay A1. .Like-' wise have been omitted those devices that I are required for calls from the subscribers of the exchange HV to otherexchanges.

lhe arrangement functions in the followrelay A is energized by the ringingj'current flowing over the main exchangeliner On being. operated, the .relay'A cl'osesits 0on tact 1 a; and thusconnects up the calling lamp AL and Wlndiligl of the relayHover: earth, contact 1 w, winding I of relay H and parallel theretolamp AL, batteryfearth'." On being operated, relay H closes the contacts 2 h and 3 h, thereby at 'contact 2 h it relay P 1, and at. contact 3 .h it closesa locking circuit for itself over: earth, con: .tacts 3 71,66, Winding I of-H,=,batte'ry, earth.

ing manner: VVhena subscriber of the main f ;exchange'SAwishesE to be connected to the *privateb'ranch ,exchange-;subscriber the prepares the circuit for energizing thetest i? Thereupon she throws the speaking key AT and answers the call.

The throwing of the speaking key AT closes a circuit over: earth, battery, contact 4 m; of the key AT, winding II of relay H, winding I of relay U, contact 5 p 1, relay B, earth. In this circuit the relay H looks itself and the relays B and U are operated. By opening its contact 6 b, the relay B interrupts the circuit of the lamp AL, which is thus extinguished. Relay U at its contact 7 it closes a locking circuit for itself over: earth, relay B, contact 7 a, winding II of relay U, contact 8 o, cut-off key TrT, battery, earth. Furthermore, at its contact 9 w it prepares the locking circuit for winding I and the short circuiting of winding II of the test relay P 1. The operator then presses the key NT associated with the wanted extension station subscriber and thereby closes the energizing circuit for the rotary magnet D of the switch VVL over: earth, contact 10 m of the extension station key MT, contact 11 at of the speaking key AT, contacts 12 t7" and 13 p 1, magnet D,

interrupter RU, battery, earth; whereupon the switch is started up.

lVhen its wipers reach the contact, which has been designated in the contact bank of theswitch L by the operator pressing the key NT and to which the wanted subscribers line is connected, the relay Tr is operated over: earth, contact 14 mi of the key NT, wiperd of the switch IVL, winding I of relay T1 contact 15 at of the key AT, battery, earth. By closing its contact 16 tr, the relay Tr closes a locking circuit for itself over: earth, relay B, contacts 5 p l, 16 fr, winding II of relay T7, cut-off key TTT, battery, earth; and at its contact 12 tr it opens the circuit of the rotary magnet D. Thereby the switch VVL is arrested when it reaches the line of the wanted subscriber, and it can be seen that this is done independently of the fact that the subscriber is free or is engaged. The relay Tr also short circuits winding II of relay H its contact 17 tr, so that H falls back slowly.

If the subscriber be free, relay P 1 is operated over the following circuit during the time H takes to fall back: earth, contacts 2 h, 18 tr, windings II and I of relay P 1, wiper 0 3 of switch IVL, winding II of relay T, battery, earth. Relay P 1 opens its contact 13 p 1 in order to prevent the switch starting up again when relay Tr falls back. It also short circuits its high resistance winding'II at contact 19 p 1, and thus marks the subscribers line engaged. Furthermore,

by opening its contact 5 '72 1 and-closing contact 20 29" 1, tl1e relay P 1 connectsup the relay P 2 over: earth, relayB, contact 20 p 1, relay P 2, battery, earth. Relay P 2 closes its contact 21 291 2, thereby establishing a circuit for the lamp ML over:

back earth, battery, lamp ML, contact 21 p 2, wiper (l of the switch IVL, contact 14 at, earth. Therefore, the lamp ML continues to burn as long as the key NT is pressed by the operator, whereby she recognizes that the wanted subscriber is free. On being operated, the relay P 2 also closes the contacts 22 p 2 and 23 2, therefore, after the key AT has been released, the ringing current, which has been applied to the lead a 3 over' contact 24 a when relay U was operated, reaches the subscriber with interruptions. The calling of the subscriber is notified to the operator by the flashing of the lamp BL, the circuit of which is closed at contact 25 w and extends over: earth, interrupter Ru, contact 25 a, lamp B1, contact 26 at of the speaking key AT, battery, earth.

IVhen the subscriber N takes down his receiver, relay S is operated over: earth, winding II of relay S, contact 27 wt of the key AT, contact 23 0 2, wiper b 3 of the switch VVL, subscribers station N, wiper a 3 of the switch IVL, contact 22 p 2, contact 29 at of the key AT, contact 24 to, interrupter BU, source of alternating current W, battery, earth. Relay S at its contact 30 s closes the circuit of relay V over: earth, contact 30 s, relay V, battery, earth. Belay V opens the locking circuit of relay U by opening its contact 8 o, whereupon U falls back and switches off the ringing current from lead a 3 by moving the contact 24 u back into the position 31 u. The falling of relay U also returns the contact 25 a, so that the following circuit isestablished for the lamp BL: earth, battery, contact 26 at, lamp BL, contacts 32 u, b, earth. The lamp BL, therefore, burns continuously and this notifies the operator'that the subscriber N has answered. On being operated, the relay V has also closed the contact 34 a), so preventing, on the falling back of relay U and the opening of contact 9 u, the circuit for the test relay P 1 being opened. As furthern'iore the contacts'35 *0 and 36 1) were closed when relay V was operated, the connection between-the main ex change subscriber and the extension station subscriber has now been established.

The release-of the connection is effected in the following manner: Relay S fallsback when the extension station subscriber hangs up his receiver. The opening of the contact 30 s interrupts the circuit of relay V, which on falling back opens at contact 34 o the circuit of relay P 1 and at its con tacts 35 a and 36 o opens the leads a 3 and b 3. By the falling back of P 1-is released the contact 20 p 1, thus deenergizing relay P 2, which opens its contacts21 39 2, 22 p 2, 23 29 2. Furthermore, the circuit of relay B is opened atcontact 20. p 1, so that it also falls back and opens its contact 33 Z); this causes the lamp to go out and the operator operated, as relay Pas is energized and has is thereby notified that the conversation has been ended.

If the subscriber be engaged, the circuit changes take place as above described till the, energizing of relay Tr. But now the relay P l and, therefore, also P 2 are not closed its contact 37 pas, hence the high resistance winding of this r'elayis short circuited and the relay P 1 in p'arallelthere with does not receive sufficient current to be operated. Therefore, the contact 38 try is closed, but contact21 p 2 is open. Hence the following circuit for lamp ML is established: earth, battery, lamp ML, contact 38 t1" interrupter RU, earth. The'lamp, there ore, flashes, so notifying the operator. that the subscriber is engaged. Thereupon the operator throws thekey RS and is thus connected to the subscriber N overthe fol-- lowing route as the contact 39 tr is closed: earth, condenser K, contact 40 rs 0f the key RS, ope'rators head set Abfl'contacts 41 m of key RS, 42 at of key AT, 39 tr, wiper b 3 of the switch WL, subscriber N, lead 011,1ead

' 0/; 2, wiper a 2 of the call seeker AS 1, feeding bridge relay A 1, battery, earth. She then informs the wanted subscriber that there is a main exchange call for him. In the mean time relay H has fallen back and opened contact 2 it, because its second winding has been short circuited over contact'17 tr when relay Tr was operated. Thus the circuit of the test relay P ,1 has been opened, so that,

after the subscriber N'has ended his con versation at the'request of the operator, the

test circuit for relay P 1 has to be again established. The operator, therefore, presses now the key and by thus interrupting the locking circuit over the second winding of relay Tr causes this relay to fall back;

so that the opening of contact 17 tr removes the short circuit from relay H, which is 45 again operated and, again closes contact 2 h. The operator then. again operates the key NT, thus again operatingthe relay Tr and again initiates all the succeeding :circuit changes asabove described, sothat the con: nection of the ,main' exchange subscriber with the extension station subscriber is thereby again established in the same manner. 3

What I claimisz" r 1. In a private branch exchange, subscrib 'ers lines, a trunk incoming from a main exchange andterminating'ina switch having access to said lines, means for marking a called line, means foroperating. said switch to hunt for the marked line,'two test wipers on said switch, means controlled over the. first of said wipers for stopping the switch on the calledline, and means controlled over the second of said wipers for determining the idle or busy condition of said line.

2. In a private branch exchange, subscribers lines, an: incoming trunk terminating inaswitchl having access to said lines,

means for marking, a called line, means for operating said switch to hunt for said-called line, a test relay for stopping said switch, in engagement with said line, a second test. relay for determining the idle or; busy con- ";dition offsaid line, and a testing "circuit, including said second test .relayjclosed by I the-'operationof saildfirst test relay. I z

V In a telephonefl system, subscriber s" lines, 'a switch having access to said lines, means for operating saidswitch to hunt for I a called one of said lines, a test relay con-;

trolled over .one wiper. of said switch for Ystopping said switch in "engagement with said called line,and: asecond test relaycontrolled over alsecondwiper'of said switch .for, determining the idle or busy condition 1 3 of said line. a V

' 4. In aprivatebranch exchange, subscrib-- ers lines, an incomingtrunk terminating in a switch having access to said lines, an operators position for intercepting. ncom ng;

I 5. Ina private lines, an operators' position, means .for op-' a test'relay for stopping said switch onthe mining the idle o'r busy condition of said line, and a signal at said operators posig 'erating said switch to hunt'foraealledline, r '1 wanted line, a second test relay for detertion jointly controlled by said test relays.

for informing the operator of the idle or busy condition of said line.

6. In a private branch scrlbers lines, a switch hav ng access to said mining the idle or busy condition of said said line. is found busy.

exchange, sublines, an operators. position I means for op-'v if erating said switch to hunt for a called line,

a test relay for stopping said switch on the I wanted line, a second test relay for deterline, and a circuit prepared by said first .test'relay for permittingthe operator to converse with the called subscriber'in case 7. In a telephone system, subscribers lines, an incoming trunk terminating in a switch having, access to said lines, an operators position for lnterceptmg lncom ng hunt for a calling line,'two line wipers and two test wipers on said switch, a test relay controlled over one of said test wipers for stopping said switch onthe called line, a" second test relay controlled over the other: test wiper for determining the :idle or busycondition of said line, a signal at said operators position jointly controlled by said test calls,-means for operating said switchto relays to inform the operator of the condition of said line, and a circuit prepared by said first relay and including only one of said line wipers for permitting the operator to converse with the called subscriber in case said line is busy.

8. In a private branch exchange, subscribers lines, a trunk line connecting said exchange with a main exchange, said trunk line terminating in an automatic switch in the branch exchange, an operators posit-ion for intercepting incoming calls over said trunk line, means controlled by the operator for operating said switch into engagement with a called one of said subscribers lines, and offering means whereby the operator can cut in on a busy line and inform the wanted subscriber of the main exchange call.

9. In a telephone system, a main exchange and a branch exchange, a trunk line connecting said exchanges and terminating in an automatic switch and an attendants position at the branch exchange, subscribers lines in said branch exchange, a signal at said attendants position operated responsive to the extension of a connection from a main exchange subscribers line to said trunk line, means controlled by the attendant for operating said switch to "further extend the connection to a wanted branch. exchange subscribers line, and means for permitting the attendant to converse with a busy called subscriber.

In witness whereof, Ihereunto subscribe my name this 21st day of March, A. D. 1930.

J OHANNES STICH.

CERTIFICATE OF CORRECTION.

Patent No. 1,812,222. Granted June 30, 1931, to

JOHANNES STICH.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 4, after line 33, insert the following as claim 10:

10. In a branch exchange wherein local calls are completed by means of subscriber controlled automatic switches and wherein all incoming trunk calls are completed by an attendant by means of automatic switches individual to the incoming trunk lines, means for signailing the attendant when an incoming call has been extended to a line has in another connection, and means controlled by the attendant for establishing a talking connection with the busy line over the apparatus used in extending the connection.

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 6th day of October, A. D. 1931.

M. J. Moore, (Seal) Acting Commissioner of Patents. 

